Nut lock



h the bend between the two threads.

Patented Aug. 21, 1945 UNITED STATES PATENT OFFICE l I. y fNUTLooKEdwardCovey Anderton, Tappahannock, Va.

AppucationMay 1o, 1944,s'eria1'No. 534,949

. 2 Claims.

My invention relatesto nut-locks; and it has for its object theprovidingof a combination of a bolt and nut `sol threaded thatwhen thenut is run down, threads `of a coarser pitch cut across Vand bend orbreak threads of a nner pitch, and jam the nut and' bolt together `byforcingparts of thel ner threads into Tthe interstices `which openbetween the two'differingthrea'ds, `which effectively prevents the nutfrom backing 01T from any accidental `causefsuch asvibration. `What Irefer to as the forcing of parts of thener thread into interstiees maybe the actual breaking off of parts of the finer thread andforcing themintointerstices, or itrriay be thedefor'mation of any partv ofl thefiner threadlbycurling it or` bending it into the adjacent interstice.When two 'threads of differing pitch arelaidupon one another it will benoted thatthe thread of one lies at anangle to thethread of `theotheryand that `when the one isV rotatedagainst' the other,

the stronger thread will exert aside-cutting force against the weakerthread, and where they come into direct `opposition the stronger thread`will either break or bend or deform the weakerithread; and the .weakerthread, `that is,the thread of udinerlpitch, will be broken off into orbent into he interstice which will exist at the point of A feature ofeters, but of the-sameroot diameter.

next valley or intersticey between the two threads. So, as thenut-advances over thebolt, more and more will the bolt thread bedeformed and'forced toward the `preceding `nut thread. fIn thisway theanterior` threads of the nut are jammed.

-A feature of myfinventi'on isthat-the finer thread does not fill thespaces between the coarser threads. If we keep to the same shape ofthread-the standard thread? having l *an* inclination of 60 degrees tothefhorizcntal, making between `any two threads -a valley of=`6`0degreesand cut the finer thread by only changing the longitudinal feedof the cuttingtool, we shall have the two threadsof differing outsidediam- It is important to note that theroutside diameter ofthe `i-lnerthread isless` that the outside diameter of `In thef'drawing, `whichforrnsa part of `this specication:

this progressive curling or bending or partial l breaking ofthe nerthread into the adjacent interstice is that it allows the nut to move inone threaded with the two differing threads, the

thread which first engages the bolt thread is cut to the same pitch asthe bolt thread; which thread is preferably the finer one. Whennecessary the nut may be given extraJ thickness to accommodate the twothreads.

Considering the action of the nut thread in `relation `to theboltthread, and when the nut is cut with the coarser thread: we shallsee that `the said coarser thread, as it engages the finer h thread,will cut and will deform the latter in the direction in which the nut ismoving. Each individual nut thread will tend to force the contiguouspart of the finer bolt thread into the Figure 1 shows a bolt having'fahcoarser thread and a finer thread.

. Figure 2 showsfin section,` thel nut to be used with the .bolt showninlFigure l.

Figure 3 shows a bolt with a thread of ne pitch only. l h

Figure 4 shows the nut, having two dlfferlng threads, to be used withthe bolt shown in Figcoarser thread 4 is cut at the end of the bolt, l

while'the finer `thread 6 is cut at` the inner or bolt-head end of thecoarser thread. Figure `2 shows the nut 8 for bolt 2, in which nut thecoarser of the two threads is cut.

It is to be remembered that in all cases the depth of the coarser threadand the depth of the :liner thread are the same. That is, the rootdiameter of the bolt is the same under each thread; and the rootdiameters of the nut threads, when they differ, are the same. There-:fore the strength of the bolt, when it bears the differing threads, isthe same throughout its length; and the 'strength of the nut, when itsthreads dilfer, is the same at either thread.

,lb .is also to be noted that the difference in pitch of the two threadsis made by changing the longitudinal feed of the cutting tool, whichchange may be made manually or automatically.

Since the setting of the cutting tool is not changed, the height of thefiner thread will be less than the height of the coarser thread. Theinclination of the` side of the thread is not changed; the width of thebase of the thread or the pitch is changed; therefore the height of thethread .is changed.

Because of the difference in the height of the two threads, the finerthread will not, of itself, fill the space between two of Ithe coarserthreads;

and the finer thread would be free to run in the coarser thread but forthe dierence in pitch;-v

form the finer thread, jamming it 'into the contiguous intersticebetween itself and the next thread.

So, when the nut 8 is run down on `thread 4 on bolt 2 andengages thefiner thread 6, the coarser threadlli willl ride` over, cut in'to, bend,break, or otherwise deform thread 6, and jam it or parts of it into the,next interstice.

In Figures 3 and 4, the iiner thread 28 is cut on the bolt 30; and thecoarser thread 32 and the finer thread 34 are cut in the nut. In thiscaserthe finer thread 34 of the nut runs down bolt thread 28k until thecoarser thread 32 .cuts into the finer vthread 28 of the bolt. Jammingensues.

In this specification I `refer to the two threads of differing pitch asthe coarser thread and the finer thread. This simply meansfthat-l one ofthe 1 ratio of thetwo pitches may well be proportioned to the use towhich the bolt is to be put, v

portion.

The action of the coarser thread against the finer thread is shown inFigure 5; wherein the movement of the coarser and steeper thread 36 isindicated by the arrow, and wherein the side cutting action of thread 36against thread 38 will be understood.

Figure 6 is designed to show the diiference in pitch and in heightbetween the coarser thread 40 and the finer thread 42 on the bolt 44;the nut 46 having the coarser thread 4 0. In considering the interactionof the two'threads: it is the coarser thread of the nut, 40, whichdeforms and jams with the finer thread 42 on the bolt.- In the drawing Ihave shown a coarse thread and a ne thread of cgnsiderable difference inpitch,vso that the difference may be clearly seen. And for the samereason, the dimensions `in Figures 6- and 7 have been magnified.

I claim:

1. An assembly of bolt and nut members in which one member thereof has athread portion of coarse pitch and an immediately adjacent portion of iepitch, while the other member has a thready of uniform pitch conformingto one of those of the rst mentioned member;xthe relative positions ofthe threadedr portions of unlike pitch being such that whether it be onthe bolt or on the nut the fine pitch portion will lie between the bolthead and the coarse pitch portion. v

2. An .assembly of .boltand nut members in which one member thereof hasa thread portion of coarse pitch andan immediately ,adjacent portion ofne pitch, the thread of coarsey pitch andthe thread of fine pitch havingthe 'same root diameterywhile the other member has a thread of uniformpitch conforming to one of those of the firs't mentioned member; therelative positions of the threaded portions of unlike pitch being suchthat whether it be on the bolt .i

or on.` the nut the `fine pitch portion will lie between the bolt headand the coarse pitch EDWARD COVEY ANDERTON.

